OPEC Secretary-General Mohammad Barkindo said on Thursday that oil producers are very concerned about spare output capacity amid a reduction in energy-industry investment.

“We are very concerned,” Barkindo said in response to a question about spare capacity, citing a continued decline in oil industry investment resulting from the market downturn.

Barkindo, speaking at the Oil and Money conference in London, also said he wanted to ensure there is no shortage of crude in the market.

Oil prices have rallied this year on expectations that U.S. sanctions on Iran will strain supplies by lowering shipments from OPEC’s third-largest oil producer.

Brent crude last week reached $86.74, the highest since 2014.

OPEC raised its forecast for growth in global oil demand last month. It now sees 2020 oil consumption reaching 101.9 million barrels per day (bpd), up 1.2 million bpd from last year’s report. Longer-term, oil demand is expected to increase by 14.5 million bpd to 111.7 million bpd by 2040.